Authorities in Switzerland have launched an investigation after dozens of urns filled with human ashes were discovered on the bed of a Lake Zurich.

The disposals are illegal unless carried out with a permit, and there are claims that they came from the nearby Dignitas clinic, which helps people to end their lives, so-called assisted suicide, which is permitted in Switzerland.

Police have refused to comment on whether there is any evidence directly connecting the urns to Dignitas, that has helped hundreds of people - including Americans, Britons, Germans and Frenchmen - take their lives in recent years, because their own countries prohibit the practice.

A former employee claims she saw the clinic's founder, Ludwig Minelli, dispose of urns in this manner.

"He always told me that they would dissolve in the water, that they were urns made of tons of clay. The reason why he did this was for financial reasons because it was very expensive to send these urns to a foreign country and he wanted to save the money," said Soraya Wernli.

Diginitas have refused to comment.